292 TEGUMENTARY ORGANS. 



mixture of saliva with three to four volumes of physiological 

 salt solution (BizzozERO, Intern. Monatschr.f. Anat., 1885, p. 

 278) ; for hard epithelia, energetic dissociating agents, such 

 as 40 per cent, solution of caustic potash. 



MINOT (Amer. Natural., xx, 1886, p. 575 ; cf. Journ. Roy. 

 Mic. Soc., 1886, p. 872) recommends maceration for several 

 days in 0*6 per cent, solution of sodium chloride containing 

 0*1 per cent, of thymol, which allows the isolation of the 

 epidermis of embryos, and is useful for the study of the 

 development of hairs. 



Another method, given by MITEOPHANOW (see Zeit. f. iviss. 

 Hilt., v, 4, 1888, p. 513), is as follows : An embryo of Axolotl 

 is fixed for a quarter of an hour in 3 per cent, nitric acid, and 

 then brought into one-third alcohol. After an hour the epi- 

 dermis begins to come away in places ; and if the embryo be 

 put for twenty-four hours into stronger spirit, it will come 

 away almost entirely. 



The elements of hairs and nails may be isolated by pro- 

 longed maceration in 40 per cent, potash solution, or by heating 

 with concentrated sulphuric acid. 



Horny tissues stain well in safranin or gentian violet 

 (REINKE, Arch. f. mik. Anat., xxx, 1887, p. 183 ; Zeit. f. wiss. 

 Mik., iv, 3, 1887, p. 383). 



614. Intra-epidermic Nerve-fibres. Must be studied by the 

 gold-method. RANVIER (Traite, p. 900) recommends the 

 boiled-formic-acid and gold-chloride method, 208. 



He also (p. 910) recommends this method for the study of 

 the tactile menisci of the pig's or mole's snout. 



Pieces of skin are impregnated as directed, 208, and 

 after reduction are brought into alcohol, which completes the 

 hardening, and stays the further reduction of the gold. 

 Sections are then made. 



For the study of the tactile menisci of the snout, Ranvier 

 also recommends the lemon-juice and gold-chloride method, 

 209. 



615. Innervation of the Muzzle of the Ox (CYBULSKY, Zeit. f. 

 wiss. Zool., 1883, p. 635; cf. Journ. Roy. Mic. Soc., 1885, p. 

 555). Cybulsky employs the method of HENOCQUE given 

 above, 211, impregnating sections of the fresh organ (made 



